1. Field of the Invention
The present invention relates to load balancing for servers in a communications network, and in particular load balancing for Point-to-Point over Ethernet (PPPoE) servers.
2. Description of the Related Art
Networks of general purpose computer systems and specialized devices connected by external communication links are well known and widely used in commerce. The networks often include one or more network devices that facilitate the passage of information between the computer systems and devices. A network node is a network device or computer or specialized device connected by the communication links. An end node is a node that is configured to originate or terminate communications over the network. An intermediate network node facilitates the passage of data between end nodes.
A network service provider (SP) often brings network service right to the premises of its subscribers, also called users and customers herein. Several user sites are connected by telephone wire, cable or wireless transmission media to user-facing provider edge intermediate network nodes (u-PE nodes) that are located close to user sites. Several u-PE nodes are connected over an aggregation network to fewer, more powerful network-facing provider edge intermediate network nodes (n-PE nodes) that provide a point of presence on the destination network. For example, when user premises end nodes are connected to the SP equipment through a digital subscriber loop (DSL) modem, those modems communicate with a u-PEs called a DSL access module (DSLAM). Several DSLAM are connected over an aggregation network to an n-PEs called a broadband remote access server (BRAS). In a typical configuration, the end nodes communicate with the BRAS using a Point-to-Point Protocol (PPP) over Ethernet protocol (PPPoE). A DSLAM is designed to handle about a thousand communication sessions, where a session is an exchange of data packets between the same user and BRAS. A BRAS host is designed to handle much larger session loads, e.g., multiples of 32,000 sessions.